Colorado Dangerous Dog Law

What happens right after the bite

The doctor who treats the bite, and anyone else who knows of it, must report it to the local public health agency¹⁴. Under the Board of Health rules, dog bites are reported within 24 hours, and the investigation is usually handed to the city or county animal control officer¹⁶. The health department then orders the owner to confine the dog for observation, at the owner's expense, at home, at a shelter or at another place it designates¹⁵. The period is 10 days, and it applies even to a vaccinated dog; rabies shots are deferred until the observation ends¹⁶. If the dog falls ill or dies, it must be tested for rabies, and the owner pays¹⁶. The state health department's rabies page lists the local agencies²³.

How does a dog become "dangerous" in Colorado?

There is no administrative hearing at the state level. The label comes from the criminal statute, § 18-9-204.5. A "dangerous dog" is one that has inflicted bodily injury or serious bodily injury on, or killed, a person or a domestic animal; one whose behaviour would lead a reasonable person to believe it may do so; or a dog trained or used for fighting¹⁷. "Bodily injury" in this setting means severe bruising, muscle tears or lacerations that need professional treatment¹⁷. A prosecutor files the charge against the owner, and the dog's status is settled in that case.

Section 18-9-204.5 leaves cities and counties free to adopt their own dangerous-dog rules, so a local code may add its own designation, hearing and appeal process on top of the state charge¹⁷. The state statute bars only one thing: local rules cannot single out breeds¹⁷.

What the charge looks like

The penalty depends on what the dog did¹⁷¹⁸¹⁹:

• Bodily injury to a person: class 2 misdemeanor, up to 120 days in jail and a $750 fine.
• Serious bodily injury to a person: class 1 misdemeanor, up to 364 days and $1,000; a second or later conviction is a class 6 felony.
• Death of a person: class 5 felony, one to three years in prison and a $1,000 to $100,000 fine.
• Injury to or death of a domestic animal: class 2 misdemeanor, with restitution to the animal's owner.

When the bite injured a person, the court must also order restitution for the victim's losses¹⁷. After an arrest or summons, the dog may be held at a public shelter at the owner's expense until the case ends¹⁷.

Defenses written into the statute

The owner has an affirmative defense if the person attacked was committing a crime (other than a petty offense) against the owner off the owner's land, or against a person or the property on it; if the person tormented, abused or provoked the dog in an extreme way; or, for attacks on animals, if the other animal was a stray on the owner's land or was attacking¹⁷. These defenses never cover a dog trained for fighting¹⁷. The statute does not apply to police dogs, to bites on vets, groomers and trainers at work, or to working hunting, herding and predator control dogs that injure another animal¹⁷.

What the owner must do after a conviction

The court must order the owner to keep the dog in an escape-proof building or enclosure, leashed whenever it is outside, with a conspicuous warning sign¹⁷. The dog must be microchipped at the owner's expense, and the owner pays the Bureau of Animal Protection a $50 license fee¹⁷. The Department of Agriculture registers the dog online with the full court order, a color photo and a microchip form signed by a Colorado veterinarian or shelter²⁰. The owner must report any move, escape, transfer or death in writing, warn every groomer, vet or trainer before service, and tell any new owner in writing¹⁷. After a second conviction, the dog must also be muzzled outside its enclosure¹⁷.

When will a court order the dog euthanized?

Euthanasia is mandatory once appeals are exhausted if the conviction involved serious bodily injury to a person, the death of a person or domestic animal, or a second violation by the same dog and owner¹⁷. If the second violation is by the same dog under a different owner, the court may order it¹⁷. Separately, in a civil lawsuit under § 13-21-124, a judge may order the dog euthanized at the owner's expense if the owner knew the dog was vicious¹. See dog bite euthanasia laws.

Breed rules and home-rule cities

The 2004 law forbids municipal and county dangerous-dog rules written by breed, and protected dogs awaiting destruction under breed bans on April 21, 2004¹⁷. Home-rule cities have not all followed it. Denver, which banned pit bulls from 1989, now admits American pit bull terriers, American Staffordshire terriers and Staffordshire bull terriers only with a breed-restricted permit renewed yearly for three years²¹. Check the city code where the dog lives.

If the dog bites again

A second conviction raises the stakes on every count: a serious injury becomes a felony, the muzzle rule applies, and euthanasia becomes mandatory for the same owner¹⁷. For the owner's civil exposure, see my dog bit someone and the Colorado dog bite law page.

Rules for a declared dog in Colorado

Colorado rules in brief

Reporting. The physician who first treats a person bitten by a dog, and any other person who knows of the bite, must report it to the local health department or county health officer¹⁴. Under the Board of Health's communicable-disease rules, dog and cat bites must be reported within 24 hours, usually through local animal control¹⁶.

Euthanasia. After a conviction for a dog that caused serious bodily injury to a person, killed a person or domestic animal, or for a second offense with the same dog and owner, the court must order the dog confiscated and euthanized once appeals are exhausted¹⁷. A civil court may also order euthanasia under § 13-21-124(3) if the owner knew the dog was vicious¹.

Criminal penalties. Owning a dangerous dog that injures a person is a class 2 misdemeanor; serious bodily injury is a class 1 misdemeanor (a class 6 felony on a second offense); a death is a class 5 felony, punishable by one to three years and a fine of $1,000 to $100,000¹⁷¹⁸¹⁹.

Breed rules. Since 2004 state law bars municipal and county dangerous-dog rules that are specific to breed, but home-rule Denver still requires a breed-restricted permit for pit bull-type dogs^17,21.

Compare states: dangerous dog laws by state, bite quarantine rules, euthanasia after a bite. If your dog bit someone, start with what happens next.

Sources

1. C.R.S. § 13-21-124, Civil actions against dog owners, Colorado Revised Statutes (public.law copy of the official text). Checked 17 October 2026.
2. Robinson v. Legro, 2014 CO 40, 325 P.3d 1053, Colorado Supreme Court (CourtListener). Checked 17 October 2026.
3. Colorado Model Civil Jury Instructions, Chapter 13: Animals, Colorado Judicial Branch. Checked 17 October 2026.
4. C.R.S. § 13-80-102, General limitation of actions, two years, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
5. C.R.S. §§ 13-81-101 and 13-81-103, Persons under disability, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
6. C.R.S. § 13-21-111, Negligence cases: comparative negligence, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
7. C.R.S. § 13-21-102.5, Limitations on damages for noneconomic loss or injury, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
8. HB24-1472, Raise Damage Limit Tort Actions (signed June 3, 2024), Colorado General Assembly. Checked 17 October 2026.
9. C.R.S. § 13-21-102, Exemplary damages, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
10. C.R.S. § 24-10-109, Colorado Governmental Immunity Act: notice required, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
11. Wilson v. Marchiondo, 124 P.3d 837 (Colo. App. 2005), Colorado Court of Appeals (CourtListener). Checked 17 October 2026.
12. HB23-1068, Pet Animal Ownership In Housing (signed June 7, 2023), Colorado General Assembly. Checked 17 October 2026.
13. HB25-1207, Pet Ownership Residential Housing Structures (signed May 22, 2025), Colorado General Assembly. Checked 17 October 2026.
14. C.R.S. § 25-4-603, Report of bites by animals, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
15. C.R.S. § 25-4-604, Confinement of animals that have bitten a person, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
16. Rabies Management of Domestic Animals Involved in a Human Bite, Weld County Department of Public Health and Environment. Checked 17 October 2026.
17. C.R.S. § 18-9-204.5, Unlawful ownership of dangerous dog, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
18. C.R.S. § 18-1.3-501, Misdemeanors classified: penalties, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
19. C.R.S. § 18-1.3-401, Felonies classified: presumptive ranges, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
20. Dangerous Dog Registration, Colorado Department of Agriculture, Bureau of Animal Protection. Checked 17 October 2026.
21. Breed-Restricted Permits, City and County of Denver, Denver Animal Protection. Checked 17 October 2026.
22. C.R.S. § 18-1-901(3)(p), Definition of serious bodily injury, Colorado Revised Statutes (public.law copy). Checked 17 October 2026.
23. Rabies, Colorado Department of Public Health and Environment. Checked 17 October 2026.